Three-dimensional ordered ZnO-CuO inverse opals toward low concentration acetone detection for exhaled breath sensing

A series of three-dimensional (3D) ordered ZnO-CuO inverse opals (IO) were synthesized by a simply polymethylmethacrylate (PMMA) template method and characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), Xray diffractometer, and Xray photoelectron spectroscopy (XPS) techniques. The performance of the ZnO-CuO IO sensors to diabetes biomarker (acetone gas) toward exhaled breath was systemically studied. The results indicate that the sensing properties of the ZnO-CuO IO sensors to very low acetone concentration are enhanced compared with that of the pure ZnO and CuO IO sensors, depending strongly on the ZnO and CuO molar ratio. The IO sensor with atom ratio of Zn/Cu = 1: 1 is the optimal one, the corresponding response is 1.4-2.4 times higher than the other IO gas sensors in this work and the detection limit is as low as 100 ppb. And more, it shows good performance to acetone under quite high humidity. The enhanced sensing performance can be attributed to the formation of p-n heterojunctions and the well-constructed 3D IO structure. The excellent sensing performance indicates that 3D ZnO-CuO IO hybrid composites are a promising functional material to actual application in monitoring and detecting diabetes in a noninvasive and more accurate way. (C) 2015 Elsevier B.V. All rights reserved.